This invention is concerned with a bonding head for a wire bonding machine for bonding wire to a contact surface of an electronic or electrical component, for example a so-called chip, and is especially concerned with such a machine for ultrasonic bonding.
Such machines are known, see for example German patent application No. P 33 43 738, and comprise a bonding head comprising a bonding tool mounted on an ultrasonic transducer, a bonding tip of the tool being arranged, in the operation of the machine, to press electrically conducting wire against the contact surface of an electrical or electronic component, the wire being drawn from a suitable wire supply, for example a spool; the machine may also include a wire clamp by which the wire drawn from the spool may be clamped, the wire clamp being movable backward and forward generally in the direction in which the wire is fed to appropriately position the free end of wire drawn from the spool after completion of a bonding operation. In many previously known machines the wire spool has been mounted above the transducer in the bonding head and the wire drawn from the spool has passed through a hole in the transducer and in a part of the bonding tool to reach a position between the bonding tip and the contact surface. This arrangement has not been altogether satisfactory.
Any change of the basic setting of the transducer and/or of the inclination of the wedge relative to the bonding pad on the electric or electronic component is practically impossible with the structure as proposed, because wire feeding occurs through the transducer. In that case the transducer and the wire spool would have to be adjusted in accordance with the changed inclination of the wedge, whereby the overall structure would become considerably more expensive. Also, with the proposed structure it is only possible to mount relatively small-sized wire spools in the bonding head, because there is only little space available for the wire spool above the bonding head. Practically no space is left for a wire tension sensor.